The invention concerns a brake with a base plate, with which a brake operating device and two brake disks are connected essentially torsion-proof, and with a friction lining arranged to move between the brake disks, connected essentially torsion-proof to an input shaft rotatable relative to the base plate, in which the brake disk facing the base plate is axially moveable and the brake disk facing away from the base plate is axially fixed during operation and kept at a spacing from the axially moving brake disk by a spacer.
Such brakes are known from the prior art and are used, for example, for externally and internally ventilated motors in traveling, traversing and hoisting mechanisms on crane units. The base plate is then connected to a fixed object relative to the input shaft, for example, a motor housing. The input shaft is connected to the power cable of the motor and rotates relative to the base plate.
By activation of the brake operating device, the friction lining is engaged with the brake disk. By friction between the friction lining rotating with the input shaft and the brake disk, rotation of the input shaft relative to the brake plate is braked and/or stopped.
The spacer serves as a stop for the brake disk so that during release of the brake, the friction lining can be released from the brake disk.
A brake of this type is disclosed in German patent document no. DE 2 660 855 C2. The base plate of the brake disclosed in this German document forms a friction surface. The actuating device and moveable brake disk are held at a distance from the base plate by a spacer sleeve. The brake in DE 2 660 855 C2 requires removal of the actuating device and the moveable brake disk when the friction lining is to be replaced.
Two publications, DD-PS 148 250 and Schiff and Hafen 47, No. 10. Pg. 64 (1995) show brakes with a cover plate that can be adjusted in the axial direction and that forms a friction surface. The disclosed brake cover encloses the interior space of the brake in which the moveable brake disk and the friction lining disk are installed. These brakes cannot function after removal of the brake cover.
However, the ordinary brakes have the drawbacks that they can only be maintained with difficulty. During maintenance, several housing parts must often be removed from the brake in time-consuming fashion and the brake taken out of service. Moreover, brake disks and friction linings of ordinary brakes wear very quickly in crane installations, in harbor use or on ships, which requires frequent maintenance. On wear of the friction lining, this becomes thinner and the looseness of the brake changes. In order to keep the braking torque constant in friction linings that are becoming thinner, the brake clearance of the brake must often be readjusted. Adjustment of the brake clearance is very labor- and time-intensive in ordinary brakes and therefore connected with high cost.
The underlying task of the present invention is to devise a brake which, in comparison with ordinary brakes, permits a very simple possibility for adjustment of the brake clearance.
This task is solved according to the invention for a brake of the type just mentioned in that a second brake disk is employed that faces away from the brake plate. The second brake disk is connected to the brake operating device in a torsion-proof manner, i.e., it is not rotatable relative to the operating device. A friction lining disk is positioned between the two brake disks, and the brake operating device is positioned between base plate and the two brake disks. During operation of the brake, the second brake disk is held in position by a spacer and fastening screw. The spacer is adjustable in an axial direction of the brake so that the free gap between the two brake disks is adjustable.
This solution is technically simple and has the advantage that the stop for the brake disk is moveable in the axial direction because of the axial adjustability of the spacer. In this manner, the brake clearance can be rapidly adjusted without considerable time expense. Since the spacer is also arranged, like the operating device, on the base plate, the brake disk need not be removed from the base plate to adjust the brake clearance.
In a particularly advantageous embodiment, the spacer can be connected to the operating device. Since the brake disk is connected to the brake operating device and this is connected to the base plate, a design unit is formed in this manner that need not be disassembled during adjustment of the brake clearance. This embodiment is also particularly advantageous when the brake is disengaged by a force exerted by the operating device, for example, a magnetic force. In this case, the brake disk is supported on the spacer during disengagement and power flow is guided directly back into the brake operating device during disengagement.
In another advantageous embodiment, the spacer can be provided at least in the region between the brake disks with a hexagon insert. The brake clearance can be adjusted particularly easily with a corresponding wrench of pliers. Other key forms of the spacer are also possible, which offer a similar adjustment possibility, for example, other polygonal shapes or holes distributed on the periphery.
In another advantageous embodiment, the spacer can have outside threading. The outside thread is cost-effective and simple to manufacture and permits precise adjustment of the brake clearance. In this context, the external thread can advantageously also be configured self-inhibiting in order to prevent displacement of the spacer and thus the brake clearance during operation of the brake.
In another advantageous embodiment, the brake disk can be fastened to the base plate with a fastening screw, in which the fastening screw extends through the spacer. This permits a particularly space-saving and simple design of the brake, in which only a single opening in the operating device need be provided for the spacer and fastening screw. The fastening screw can then run coaxially to the spacer.
Optimal power flow in the brake is obtained if, in another advantageous embodiment, the fastening screw is connected to the base plate. The braking force exerted on the fastening screw by the brake disk is directly introduced to the base plate on this account.
In another advantageous embodiment, the housing can be designed as a bell-shaped hood, which is supported sealed on the base plate and forms a brake interior sealed water-tight at least relative to the surrounding of the brake, in which the brake operating device, the friction lining and the brake disk are accommodated. This has the advantage that the brake is easier to maintain because of the bell-shaped housing than ordinary brakes. All essential components of the brake are arranged in the bell-shaped housing with the brake operating device, the friction lining and the brake disk, which can be subject to wear and/or must be regularly maintained. During removal of the bell-shaped hood, these components are freely accessible. The brake remains functional despite the removed hood, since the brake cooperating device, the brake disk and the friction lining are connected to the base plate. In this manner, the function of the brake can be easily checked during maintenance work.
At the same time, no water can penetrate into the interior space of the brake in the brake according to the invention, since the hood is supported tight against the base plate. Wear of the brake is significantly reduced by this. Oxidation of the components in the brake interior, which is favored by the abrasion products of the brake disk remaining in the brake interior, can no longer occur. The components of the brake interior also remain dry in extremely wet and aggressive surroundings. The lifetime of the brake is thus increased precisely in crane installations in harbor areas, which are exposed to aggressive sea water.
In an advantageous embodiment of the invention, a sealing element can be arranged between the base plate and hood. This modification leads to lower manufacturing costs, since precisely adjacent and flush sealing surfaces of the base plate and hood can be dispensed with. Such sealing surfaces must satisfy high tolerance requirements. On the other hand, sealing elements are easy to introduce and compensate for irregularities in the supporting surfaces of the base plate and hood. In particular, this sealing element can be designed as an O-ring.
The embodiment of the brake with a watertight sealing of the brake interior is advantageous, independently of the viewpoint of the configuration of the fastening screw and spacer, so that independent protection is sought for this embodiment.
In other advantageous embodiment, the hood can be connected to the brake operating device. In this variant, no fastening devices need be provided on the base plate for the brake operating device. The base plate can, therefore, be designed as tight plate having no openings through which liquid can penetrate into the brake interior. If the brake operating device and/or the brake disk are connected to the base plate, a design is obtained in which the hood can be easily removed from the brake and operation of the brake is guaranteed particularly simply with the hood removed. It should be kept in mind that the brake disk is axially moveable relative to the base plate in order to permit engagement and disengagement (release) of the brake.
In another advantageous embodiment, it can be prescribed that the bearing points of the brake disk and/or brake operating device are situated exclusively on the base plate. In this case, during loosening of the hood, the brake disk and/or brake operating device remain on the base plate. This also leads to a very simple design configuration of the hood and to a possibility of maintenance of the brake with the hood removed.
Additional devices, like tachometer spindles, can be connected to the input shaft when, in an additional advantageous embodiment of the brake, a flange essentially coaxial to the input shaft is formed on the outside of the hood with a through opening coaxially to the input shaft. The coaxial flange permits attachment of the additional devices to the hood. The coaxial through openings permit lengthening of the input shaft through the brake.
Since the friction lining is subject to abrasion and as a result wear, it is necessary to check the thickness of the friction lining at regular maintenance intervals. Moreover, condensation water can occur in the brake interior, which must be released from time to time. For this purpose, in another advantageous embodiment of the brake, a continuous maintenance opening can be provided which can be closed airtight and/or watertight with a closure element. The maintenance opening can then be arranged on the periphery of the hood in the radial direction relative to the input shaft. Because of the radial shape of the opening, condensation water automatically runs off the maintenance opening situated on the bottom. Moreover, the thickness of the friction lining and brake disk can be inspected through the maintenance openings. The maintenance opening, which runs parallel to the input shaft, can be advantageous for manual release of the brake and has a condensation water discharge hole in a vertical incorporation position. The maintenance opening is expediently designed as a threaded hole, which is preferably closed water- or airtight by a closure screw. The closure screw can have sealing elements, like O-rings, which lead to a particularly tight closure of the threaded hole.
In order to be able to still release seized brakes, for example, after long-term braking and wear of the brake disk and friction lining, in another advantageous embodiment a manual disengagement device, that is moveable relative to the hood, can be provided, which can be transferred to a disengagement position. The brake is released in the disengagement position. The manual disengagement device is mechanically and/or hydraulically connected to the brake disk and/or friction lining. By operation of the manual disengagement device, the brake disk is released from the friction lining. The force applied to the brake disk and/or friction lining by the manual disengagement device is preferably greater than the force applied by the brake operating device so that during defective function of the brake operating device, the brake can be released by the manual disengagement device.
Particularly ergonomic handling is obtained if, in another advantageous embodiment, the manual disengagement device is designed as a lever, which is mounted to pivot on the hood on at least one bearing. High forces for release can be introduced to the brakes by a lever without having to incur high design costs.
In order to avoid entry of water or other corrosive media into the brake interior through the bearing, the bearing can be provided in another advantageous embodiment with at least one bearing seal, through which the bearing is sealed watertight and/or airtight.
A particularly loadable bearing of the manual disengagement device on the hood is obtained if, in another advantageous embodiment, two bearings are provided on two essentially opposite positions of the hood relative to the input shaft and to each other. With this embodiment, very large forces can be introduced into the brake without the hazard of damage to the bearing.
Moreover, in an advantageous embodiment for manual release of the brake an axially moveable disengagement device can be provided through which one brake disk can be moved in a direction away from the other brake disk and the brake disengaged on this account, during which the one brake disk is held at least indirectly by the disengagement device on the base plate when the other brake disk and/or friction lining is removed. The disengagement device therefore fulfills a dual function in which it serves for both release of the brake and also as a maintenance aid, through which the one brake disk can be kept on the brake during maintenance work and need not be disassembled from the brake.
The embodiment of the brake with the disengagement means and disengagement device for manual disengagement of the brake are advantageous independently of the viewpoint of a watertight sealing of the brake interior, so that independent protection is also sought for this embodiment.
In another advantageous embodiment, a brake can have an electronic monitoring device, which is preferably arranged within the hood and through which a signal can be released that represents the function and/or wear of the brake. This electronic monitoring device can be designed, for example, in the form of a microswitch and/or in the form of a proximity switch. The microswitch, like the proximity switch, is capable of recording engagement of the brake or issuing a signal when the thickness of the friction lining falls short of a minimum. This signal can be required, for example, for maintenance purposes in order to be able to establish without intervention on the brake when the friction lining or brake disk must be replaced.